Manufacturing of semiconductor devices may include multi-step epitaxy, wherein device formation processes may be performed between successive epitaxy processes. Conventionally, device regions formed in the different epitaxial layers are adjusted to each other by aligning exposure masks to an alignment mark formed prior to the epitaxy processes in a base substrate onto which the epitaxial layers are successively grown. Typical alignment marks are based on grooves etched into the base substrate and imaged into an exposed surface of the respective epitaxial layer. Typically, high epitaxial growth rates reduce the overall process time and increase manufacturing efficiency. High epitaxial growth rates, however, tend to deform the alignment marks imaged from the base substrate into the exposed surfaces of the epitaxial layers such that at high growth rates the epitaxy distorts the alignment marks and an optical alignment device cannot reliably detect the alignment marks imaged into the exposed surfaces of the epitaxial layers. As a consequence, device regions formed in different epitaxial layers can be misaligned with respect to each other. An etching process may recover the original shape of alignment marks after epitaxy to some degree.
It is desirable to align device patterns in successively grown epitaxial layers at less effort.